Theory 092/Veterinary Medicine
Herd Immunity Is Age Mixing
The claim
Herd immunity thresholds in livestock are set by mixing between age groups rather than by R0 alone.
01The mechanism
Separated age cohorts allow the pathogen to persist in one group while another is naive; mixing determines whether immunity is effectively global.
02Predictions
- P1Thresholds should shift with mixing structure.
- P2Equal R0 with different mixing should need different coverage.
03Refutation
Thresholds tracking R0 would remove the mixing term.